A mobile robot used for maintenance inspection, cleaning, or the like on a wall surface of a structure needs to run along the wall surface. As a method which can run along the wall surface, in a case where the wall surface is a magnetic body, it is conceivable to provide a mechanism which is attracted on the wall surface by magnetic force.
As a mobile robot including a magnetic attraction mechanism, a mobile robot which can generate magnetic attraction force on a running surface by using a magnet to a driving wheel is proposed in the related art (See Japanese Patent Unexamined Publication No. 2014-73745).
FIG. 7 is a view illustrating outline of magnetic body flat surface attraction mobile device 21 in Japanese Patent Unexamined Publication Mo. 2014-73745. Vehicle body 22 of magnetic body flat surface attraction mobile device 21 includes magnet wheel 23 which can be driven and rotated. Magnet wheel 23 includes magnetic attraction force and an outer circumferential surface thereof includes depressions and projections by arranging projection portions 27 in a circumferential direction. Magnetic body flat surface attraction mobile device 21 is provided with tail portion 29 including magnetic attraction force rearward with respect to a direction of arrow A. Here, it is assumed that magnetic body flat surface attraction mobile device 21 also runs on flat surface forming member 25 which is a member forming a step with respect to flat surface 24, in addition to running on flat surface 24. Flat surface forming member 25 is present to be parallel at a fixed distance with respect to flat surface 24, and step 26 is present between flat surface 25b which is an upper surface of flat surface forming member 25 and flat surface 24.
Magnetic body flat surface attraction mobile device 21 runs on flat surface 24 in a direction of arrow A in FIG. 7 by magnet wheel 23 being rotated in a direction indicated by arrow B in FIG. 7. Magnetic body flat surface attraction mobile device 21 moves forward until a recess between projection portion 27 and projection portion 27 of magnet wheel 23 reaches end edge 25a of flat surface forming member 25 while running on flat surface 24. At this time, projection portion 27 is in contact with flat surface 25b, which is the upper surface of flat surface forming member 25. By further rotating magnet wheels 23 in this state, a rotation motion is started about a contact point between end edge 25a of flat surface forming member 25 and magnet wheel 23, and magnet wheel 23 can be pulled apart from flat surface 24 before step 26 and transferred to flat surface 25b having step 26.
Thereafter, following forward running of magnet wheel 23 on flat surface 25b, magnetic body flat surface attraction mobile device 21 allows tail portion 29 to move over step 26 by transferring tail portion 29 from original flat surface 24 to flat surface 25b having step 26.
According to this method, even in a case where it is necessary to move over the step in the middle of the running surface, since the driving wheel can be always attracted to at least one of the first running surface before the step and the second running surface after moving over the step, the mobile robot can always maintain magnetic attraction force with respect to the running surface.